Radio receiving apparatus



Jan. 19

27 e. H. STEVENSON RADIO RECEIVING APPARATUS Filed August 24, 1921 2 Sheets-Sheet 1 gag/W 247w 1, 1 1927 a. H. STEVENSON 6 2 952 RADIO RECEIVING APPARATUS Filed August 24, 1921' 2 Sheets-Shoev 2 Pas ha-4.1927.

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This invention. relates to ap aratus.

n object ofthe invention is. to provide a plurality of apparatus units which may a be separately supplied to be connected together in different combinations to consti- H tute a radio receiver.

' Another object'of the invention is to provide means for shielding a thermionic repeating device from external electrical disturbances.

A feature of the invention is a. shield which serves both for protecting a thermionic repeater from disturbances and also as a portion of the mounting structure.

Another feature of the invention is a mounting for removable coils of a loose coupler. Y

Other objects and features ofthe invention will be apparent upon consideration of the following detailed description taken in connection with the accompanying drawing in which Fig. 1 illustrates in perspective, a radio receiving set embodying the invention; Fig. 2 a general schematic diagram of the circuits of the apparatus of Fig. 1; Fig. 3 a-perspective of the apparatus mounted on the back of a thermionic repeater panel, and Fig. 4 a dlagram' 30 of the circuits and shielding arrangements of the thermionic repeating units.

Referring to Fig. 1, a receiving set is shown consisting of five associated panel units 1, 2, 3, 4: and 5. Panel 1,\which 1s the primary receiving circuit panel, carries the antenna and ground connection terminals, a condenser switch 6, and a condenser adjustment knob 7. Panel 2, the secondary receiving circuit panel, carries a stand-by switch 8 and a condenser adjustment knob Panels 3, 4 and 5 belong to the thermionic repeating units and each carries a filament current rhcostat 10 andjacks 11. These five panels are mounted side by side on a framework 12 to which they are attached by screws 13. Each panel is provided wit aligned contact terminals 26 which may be electrically connected with similar terminals on the adjacent panels by means of connecting strips 27. A top plate 14 also attached to the framework serves as the base portion'of a loose coupler for electrically coupling the rimary and seconda units. A slider 15 15 mounted for longitudinal movement in a slot 16 in which it is confined radio receiving slider 15.

in any suitable manner. coup coil1 7 'of annular form such as the we -known supporting arms 19 which extend to a point beneath the coil and are'connected at their lower ends to plugs 20. A lateral reinforcing strip 20 of insulating material, ex-

tends between the plugs and serves to brace the arms 19 in lateral direction. The terminals of the coupling coil 17 are electrically connected respectively to'the two U- shaped supporting arms 19 which are electrically connected to the plugs 20 by screws which extend through the reinforcing strip 20. The plugs 20 fit into 'acks 21 in the Asimilar couplingcoil 22 is supported on plugs which fit into jacks in a circular plate 23 mounted for rotation about its vertical axis in the plate 14. It Wlll be apparent that by, rotating the plate 23 and moving the slider 15 any desired relative angular position and separation of these couphng co ls may be obtained. Contacts 24 at one end of late 14 and contacts 25' at' the opposite en of plate 14 are respectively connected to the terminal jacks of coils 22 and 17, thus permittin subst1tut1on of any other form of trans ormer or coupling arrangement, if desired.

Referring to Fig. 2 in which the five units are each shown in dotted outline, the conductor 28 is connected to the antenna terminal of unit 1, and this terminal is in turn connected to the switch contacts 29 and 30 of condenser switch 6.- The blades of switch 6 are connected to the opposite terminals of. a variable condenser 31, the capacity of which may be varied by operation of the switch handle 7 shown in Fig. 1. One terminal of the condenser is also connected to the upper connecting terminal 26 of unit 1 and to jack 32 of the primary coupling coil 22, the other jack of which is connected to ground. The switch contact 33 of switch 6 is also directly connected to ground. It will be apparent that with switch 6 thrown to the left, the primary circuit will include the aerial conductor 28, condenser 31 and rimary coupling coil 22 in series to ground. his is indicated by the label at the left of the condenser .switch on the front of the unit 1 as shown in Fig. 1. With the condenser switch thrown to the right, the condenscr 31 and primary coupling coil 22 will be in parallel, forming a branched circuit tom the aerial to ground. A ground connection is made to the lower contact terminal 26 of unit 1, and both the contact terminals 26 of this unit are connected by strips 2? to similar contact terminals 26 of unit 2.

The secondary coupling coil 1'? or" unit 2 is electromagnetically coupled with the. magnetic coil 22 of unit 1 as previously described and terminates in jacks, one of which is connected to the ground contact terminal 26 and the other ot-which is connected to the contact 3st of stand-by switch 8. The two blades of the stand-by switch are electrically tied together. When this switch is thrown to the left to engage its contact 86, it serves merely to extend a connection from the upper and lower contact elements 26 of unit 1 to the corresponding contacts of unit 3 and to leave all the other apparatus 01" unit 2 idle. With switch thrown to the right, a secondary circuit comprising coil 17 and variable condenser 37 is completed and connections are made from the terminals of the condenser 3? to the contacts of unit 3. Condenser 37 is arranged to be varied by the knob 9 as indicated in Fig. 1.

The three repeating units 3, at and 5 each have one contact element 26 connected by strips 27 to extend the ground connection. These three units are also provided with bus-bars 38 and 39 Wl'llCll may be continuous or may be connected through contact elements such as 26 and strips 27. The latter arrangement is illustrated. A space current source E which may for example have an electromotive force of about volts is connected with its positive terminals to the bus-bar 38 and its negative terminal to the ground contact terminal 26. A filamentheating current source E. which may be of about a volts electromotive force has its positive terminal connected to bus-bar 89 and its negative terminal to the ground connection.

Unit 3 is arranged to serve as a demodulator. Units i and 5 have amplifiers tor the demodulated currents. The demodulator element 40 comprises a three-element thermionic device, preferably highly evacuated, having its filament connected to the ground connection and bus-bar 39 through a fixed resistance 41 and a filament-current rheostat 10. The impedance control element or grid of the demodulator is connected to the upper contact element 26 of unit 3, through a stopping condenser 42. high resistance 43 serves as a grid lealr to connect the grid and cathode. The anode is connected to a contact element 26, through the normally closed contacts of jack 11. A capacity element of high impedance for the o: trequency deinznlulated waves sci" as a hypass for high frequency energy in the output circuit of the demodulator. The output circuit of the demodulator is coupled to the input circuit of amplifier unit l by means of a transformer 46. This amplifier unit comprises an electrical disclrirgedevice it? which may be similar to that of demodulator t0 and may have its filament similarly connected to bus-bar 39 and ground. The secondary winding of transformer i6 is can nected to the grid and cathode of amplifier a l, the output circuit of which is connected to the input circuit of amplifier 48 by an arrangement identiral-with that connecting denunlulator 40 and amplifier 427. Space current is supplied to each of the thermionic devices 40 and 47 by source E the positive terminal of which is connected to the various anodes through bus-bar 38 and the primary winding of a transformer. A receiver 50 is equipped with a cord terminating in a plug 51 adapted to cooperate with jacks 11. if the plug 51 be inserted in the jack ll of unit 3, it will open the normally closed contacts of this jack, thus cutting oh" units 4 and 5 from the radio receiving circuit. A space current path will be completed through conductor 52. If, however, the plug 5ll1e inserted in the jack ll of unit 4, unit 5 only will be cut oft. If the plug 51 be inserted in the jack 11 of the last unit, it will complete a space current path through condoctor 52 of that unit and all three of the thermionic repeating devices will be active. The circuit arrangement of the a paratus is very flexible. The primary con enser 31 may be connected either in series or in parallel with the primary coupling coil 22. This primary circuit mav be directly connected to the input terminals of the demodulator 40 or it may be inductively connected to the demodulator through the closed tuned circuit of unit 2. \Vith any of these arrangements, demodulator 40 may be used alone or in conjunction with one or two of the thermionic amplifiers. These various circuit arrangements are all obtainable by operation of two switches 6 and 35, and the plug 51.

Fig. 3 illustrates the apparatus mounted on the back of a thermionic repeating panel such as 4. A chair-shaped plate 60, preferably of brass or other conducting material, is provided with integral lugs 61, 62 and 63 by which it may be bolted or otherwise attached to the panel. Seated on the plate is a socket member 68 in which is mounted the thermionic repeater 47. The fixed resistance 41 of the filament circuit is also mounted on the a per side of the plate. A lug 64 extending townwardly from the horizontal portion of late 60 and a lug 65 extending at right ang es to the lower vertical portion, serve to mount a strip of insulating material 66 upon which are carried the various bus-bars or the extra contact elements 26. The lower vertical portion of plate 60 has been broken away to show the external casing of transformer 46 which is attached thereto by bolts 67. In the case of unit 3, condensers 42 and 44 may be mounted in the position occupied by transformer 46 in the other units.

Referring to Fig. 4, the general arrangement of the apparatus of the repeater units with respect to the various shields 60 is shown in diagram. The thermionic discharge devices are mounted close to the chair 1.! portions of their respective shield members 60 which are separated by a very small space. This substantially divides the repeating units .into six sections, each of which is shielded from the others. It further serves to pre vent the output energy of one thermionic denocted in tandem, and chair shaped shields vice from being directly impressed upon the output circuit of a succeeding device and to a degree, it enables separation of the input circuit leads and the output circuit leads of an individual clischar e device. By reason of the effective shielding between the individual repeater units it is possible to connect several amplifiers in tandem without producing singing or local oscillations. Although the features of the invention have been disclosed as embodied in certain specific radio apparatus, it should be understood that they are capable of general application and that the invention is not to be limited to the specific arrangement disclosed, but only by the scope of the appended claims.

What is claimed is 1. A plurality of electric repeaters conof conducting material placed between adjacent repeaters upon which said repeaters are respectively mounted.

2. A repeater unit comprising a panel, a chair-shaped member attached thereto and extending laterally thereacross, and a repeater mounted on the seat portion of said chair-shaped member.

3. A repeater unit comprising a panel, a chair-sha ed plate of conducting material connecte thereto and havin its principal portions substantially perpen icular thereto, and repeating apparatus mounted on said plate whereby, when said unit is associated with other similar units, its circuits will be electrically shielded therefrom.

4. The combination in a repeater assembly of a plurality of repeaters, chair shaped supports, a repeater mounted on the seat portion of each support, said supports being attached to insulating panels and so placed as to shield said repeaters against mutual interaction.

5. A receiving apparatus comprising a plurality of units each mounted on an individual panel, means for mounting said panels in lateral alignment, a rounded supporting member on each 0 said panels carrying the apparatus of its respective unit, said supporting member serving to electrically shield its apparatus from that ofthe adjacent units.

6. An electric shield of conducting material in one piece, an individual panel attached thereto and means for the attachment and support of repeater apparatus on said shield and panel. l

In witness whereof, I/hereunto subscribe my name this 6th day of August A. D., 1921.

GEORGE H. STEVENSON. 

